The invention is based on an electronically controlled braking system.
According to the state of the art, as described, for example, in an article entitled xe2x80x9cElektronisch geregelte Nutzfahrzeugbremse [Electronically Controlled Commercial Vehicle Brake]xe2x80x9d in ATZ Automobiltechnische Zeitschrift 96 (1994) September, No. 9, electronically controlled braking systems in commercial vehicles are known. These systems feature at least one pressure control valve and at least one pressure regulation valve, or at least one pressure control valve, at least one pressure regulation valve, and at least one pressure regulation module. The pressure control valve is assigned to one vehicle wheel and is designed for wheel slippage-dependent control of brake pressure applied to a brake of the wheel and generated by a braking power actuator or a brake valve that can be activated by the driver or by a pressure regulation valve. The pressure regulation valve is designed for generation of driver-controlled brake pressure and features a pressure sensor to monitor brake pressure, as well as control electronics, with which the brake pressure can be regulated, by the comparison, between the pressure reference value and the actual value, wherein the pressure is applied axlewise or sidewise. This pressure can be transmitted to the wheel-specific pressure control valve, of which there is at least one. The pressure regulation module is designed for generation of driver-controlled brake pressure and features a pressure sensor to monitor brake pressure, as well as control electronics, with which the brake pressure can be regulated, by variance comparison, axle-by-axle. The pressure can be transmitted to at least one wheel brake, and can be controlled on a wheel-by-wheel basis depending on wheel slippage. The central control device only communicates with the pressure regulation valve, of which there is at least one, and the pressure regulation module, of which there is at least one. Alternatively, the pressure regulation valve, of which there is at least one, or the central control device only communicates with the pressure control valve, of which there is at least one, and with the pressure regulation valve, of which there is at least one. Brake pressure generated by the driver-actuated brake power actuator or the brake valve can be directly applied, to the pressure control valve.
Wheel slippage-dependent controls for ABS (Anti-Lock Braking System) and/or TCS (Traction Control System) are integrated into the electronic braking system. This is done so that each brake pressure value is also controlled, depending on the rotational behavior of the braked wheels, by the pressure control valves positioned downstream from the pressure regulation valves close to the wheels.
During this process, however, the data transmitted from the pressure control valves and sensors to the central control device, and in the opposite direction, must travel relatively long distances, which is disadvantageous for fast wheel traction control systems. Furthermore, the braking system described above is very costly to execute, especially in multi-axle vehicles, due to the high cost of assembly and cable installation required to connect the sensors and valves, which are arranged at a considerable distance, with the central control device.
German patent document DE 42 27 083 A1 describes an electronic braking system for road vehicles, in which the entire electronic system is divided into two units that communicate with one another. One electronic unit is assigned to the electronic unit of a pressure regulation module and the other electronic unit is assigned to up to two pressure control valves.
European patent document 0 652 146 A1 discloses an electronic braking control system with a multitude of pressure control valves, which are assigned local regulating units that communicate with a central control unit. In this braking system, a portion of the ABS control logic of a wheel is accomplished by the local regulating unit assigned to the applicable wheel, while the remainder of the ABS control logic for this wheel is accomplished by the central control unit. Because, in order to execute the ABS function, the central control unit must communicate with the local regulating units of the pressure control valves, connection cables suitable for this purpose must be provided or, if a data bus exists, it is occupied by the applicable data, which has a negative effect on the cost of cable installation and/or the data transmission speed.
In contrast, the purpose of the invention is to develop an electronically controlled braking system in which the drawbacks mentioned above are avoided.
This purpose is solved by providing an electronically controlled braking system, comprising a central control device (Z1; Z2), at least one pressure control valve (A) and at least one pressure regulation valve (B), or at least one pressure control valve (A), at least one pressure regulation valve (B) and at least one pressure regulation module (C), wherein a) the pressure control valve (A) is assigned to one vehicle wheel and is designed for wheel slippage-dependent control of brake pressure applied to a brake of the wheel and generated by a braking power actuator and/or brake valve that can be activated by the driver or by a pressure regulation valve (B), b) the pressure regulation valve (B) is designed for generation of driver-controlled brake pressure and includes a pressure sensor to monitor brake pressure, as well as control electronics, with which the brake pressure can be regulated, by variance comparison, either axle-by-axle or side-by-side, and can be transmitted to the wheel-specific pressure control valve (A), of which there is at least one, c) the pressure regulation module (C) is designed for generation of driver-controlled brake pressure and includes a pressure sensor to monitor brake pressure, as well as control electronics, with which the brake pressure can be regulated, by variance comparison, axle-by-axle, and can be transmitted directly to at least one wheel brake, and can be controlled on a wheel-by-wheel basis depending on wheel slippage, and d) the central control device (Z1) communicates only with the pressure regulation valve (B), of which there is at least one, and the pressure regulation module (C), of which there is at least one, or only with the pressure regulation valve (B), of which there is at least one, or e) the central control device (Z2) only communicates with the pressure control valve (A), of which there is at least one, to which brake pressure generated by the driver-actuated brake power actuator and/or brake valve can be directly applied, and with the pressure regulation valve (B), of which there is at least one, wherein f) a wheel slippage-dependent control for each braked wheel is additionally integrated into the control electronics of the pressure regulation valve (B), with which control an electric trigger signal can be generated for each pressure control valve (A) downstream from the pressure regulation valve (B).
The advantage of the electronically controlled braking system according to the invention is that, because of the complete integration of the wheel slippage-dependent control systems, such as ABS and/or TCS, into the regulating electronics of the pressure regulation valves, the corresponding connection lines between the central control device and the pressure control valves close to the wheels are eliminated, as the pressure control valves are triggered directly by the pressure regulation valves arranged on the chassis. A trigger signal for one or more wheel-specific pressure control valves is generated by the pressure regulation valves dependent on the difference between a measured actual rotational speed and a reference rotational speed. The resulting narrow wiring harness between the driver""s cab and the chassis is advantageous, especially in commercial vehicles, as the driver""s cab in such vehicles is tilted relative to the chassis, so that thick wiring harnesses run the risk of becoming kinked.
Furthermore, the CAN bus normally used for communication between the central control device and the regulating electronics of the pressure regulation valves proximate to the wheels is relieved, thus allowing for higher data transfer rates. In addition, due to the low manufacturing penetration that has become common practice today, the chassis and body of commercial vehicles are produced by different manufacturers. Consequently, and according to the invention, the bulk of the braking system, including the wheel slippage-dependent regulating electronics, can be pre-assembled on the chassis, so that during subsequent assembly of the body by partner companies very few additional steps are required to complete the braking system.
Advantageous enhancements and improvements of the electronically controlled braking system are possible by means of the measures described herein.